This glossary was first written in connection with water treatment texts. However it seemed a little silly to just restrict it to that use. So it is presented below as an aid to understanding any modern steam text. It will be added to as time progresses. If you have a specific term you would like to see a definition for and I will get onto it!
In time it is intended to turn this into an illustrated glossary.
AAR - Association of American Railroads.
ACE - American Coal Enterprises.
ACR - Alfred Country Railway, 2' (60cm) gauge line from Port Shepstone to Harding, South Africa.
Alkalinity - Anything having a pH greater than 7. All alkalis have a low concentration of hydrogen ions.
Alfloc - An internal boiler water treatment regime developed by BR and ICI.
Antifoam - A substance added to boiler water to control the foaming which naturally occurs in a body of impure water subject to rapid circulation currents.
ASME - American Society of Mechanical Engineers.
Blowdown - The process of opening a valve, normally in the lower regions of a boiler, which expels water but also dissolved and suspended solids in that water. A way of reducing the TDS/pH.
Boiler Foam Height Monitor/Meter - An electrical device giving an accurate display of boiler water foam height and solidity.
Boiler Plug - A threaded plug of solid construction fitted to boilers. Removal allows inspection and washing out.
Button Plug - Also known as a drop plug. A form of fusible plug containing a fusible material and a solid core of none fusible material. On overheating the fusible material melts releasing the solid core. The stated advantage is failure is complete, that is the entire diameter of the plug's central hole is opened on melting of the fusible material. A plug with a core of fusible material only can partially melt, leading to a very small discharge of steam and water, which can lead to low water levels not being brought to the attention of the operators.
BR - British Railways.
BRB - Brienz Rothorn Bahn, Switzerland.
C-GPCS - Cyclonic Gas Producer System.
Carbonate - An anion with a charge of -2. In the context of Porta Treatment carbonate ions form the bulk of the alkalinity in the boiler water.
Carryover - In the context if water treatment/boiler water. The fine, often unnoticed, phenomena of water drops, dissolved and suspended solids being carried out of the boiler by escaping steam. It is not the same as priming, see Steam Contamination below. Also see Firebed Carryover.
Caustic Embrittlement - Essentially this is the weakening of metals through the action of hydroxide ions. It is a complex problem which requires several causes to be present at the same time. It may be rare but must be guarded against.
Caustic Embrittlement Detector - Also known as the Schroeder Embrittlement Detector. A device attached to boilers which allows boiler water to leak past a suitably stressed piece of metal to see if it causes embrittlement.
Clay - Solid particles contained within feedwater. These generally collect at the low points of the boiler where they form a sticky clay like substance. This clay is largely immobile and thus causes localised overheating and circulation problems. Much the same as mud.
Corrosion - This take several forms. The principle forms of concern in locomotive boilers are galvanic corrosions, essentially, but not exclusively, caused by the use of different metals and oxidation corrosion caused by dissolved oxygen contained in feedwater. It must also be noted that in all water areas corrosions also occurs in water tanks, pipework, valves, injectors, clacks etc.
Defoamer - A chemical which is meant to totally remove the ability for boiler water to "foam", that is to create a foam layer above the water surface.
DLM - Dampflokmotiv und Maschinenfabrik. Modern steam company in Switzerland.
Drop Plug - A form of fusible plug containing a fissile material and a solid core of none fissile material. On overheating the fissile material melts releasing the solid core. The stated advantage is failure is complete, that is the entire diameter of the plug's central hole is opened on melting of the fissile material. A plug with a core of fissile material only can partially melt, leading to a very small discharge of steam and water, which can lead to low water levels not being brought to the attention of the operators. Also known as a button plug.
DTC - Doña Teresa Christina Railway, Brazil.
Exhaust Ejector - Whilst generally used when referring to advanced locomotive exhaust systems such as the Kylpor and Lempor it, in reality, applies to all steam locomotive exhaust systems designed to create a partial vacuum in a locomotive smokebox.
FCAF - Ferrocarril Austral Fueguino, world's most southerly railway located near Ushuaia, Rep. de Argentina. 50cm gauge.
FCGB - Ferrocarril Nacional General Belgrano, Argentine metre gauge system.
FCGR - Ferrocarril Nacional General Roca, Argentine 5'6"/1676mm gauge system.
FCGU - Ferrocarril Nacional General Urzquiza, Argentine standard, 4'8 1/2"/1435mm, gauge.
Feedwater - Any water which is fed into the water tanks of a locomotive for use in the boiler.
Fibrecsope - An inspection device with an eye piece at one end of fibre optics enabling viewing of otherwise non-visible features. Normally equipped with a lamp.
Firebed Carryover - The entrainment of solid particles from a firebed causing then to be lifted from the fire. They can be deposited in any part of the firebox, boiler tubes and smokebox or ejected from the chimney.
Foaming - The formation of a foam layer on the surface of the boiler water. It naturally occurs in a body of impure water subject to rapid circulation currents. The greater the amount of impurities dissolved in the water the greater the propensity there is for foaming.
Fouling - Anything which adheres to boiler surfaces causing localised overheating and/or disrupts water circulation. It must also be noted that in very bad water areas fouling also occurs in water tanks, pipework, valves, injectors, clacks etc.
FR - Ffestiniog Railway, UK.
Fusible Plug - generic term for a low water device in a steam locomotive boiler. A plug, normally in the roof of the firebox, contains a fissile core which, on overheating (normally when not covered by water on the water side), melts. It is meant to alert the operator to the low water level.
Gauge Frame - An attachment on boilers to allow the water level to be determined. Normally of two types, either tubular or reflex.
Gauge Glass - Clear glass fitted to a gauge frame through which the boiler water level can be seen. Normally either tubular or "flat" in the case of reflex gauge frames.
GCR - Grand Canyon Railway, USA.
GPCS - Gas Producer Combustion System.
Hard Water - Water with a high mineral (impurity) content.
Hand Hole - An oval opening (approximately hand sized) in the boiler plate allowing access for inspection and washing out.
Hand Hole Door - A solid oval piece of metal with a threaded shaft extending from the middle. The door fits through a hand hole (approximately hand sized) and butts against the inside of the outer boiler plate. A clamp fits over the shaft which is bolted down sealing the door against the boiler plate.
ICI - Imperial Chemical Industries.
ICOHTEC - International Committee for the History of Technology.
Ing. (as in Ing. L.D. Porta) - Literally this an abbreviation of Ingeniero, Spanish for engineer. The term Ing. is bestowed on any qualified engineer much in the way 'doctor' is within English speaking cultures.
Internal Boiler Water Treatment - A regime of adding chemicals to boiler feed water to treat that water whilst in the water tanks and boiler.
INTI - Instituto Nacional de Tecnologia Industrial. The Argentine state technology institute.
KLR - Kirklees Light Railway, UK.
Lineside Treatment - Any treatment of feedwater carried out prior to the water being transferred to the locomotive's water tanks.
LLAV - La Locomotive à Vapeur, book by André Chapelon. Two issues, 1938 and 1952. 1952 edition is available in English.
LVM - Locomotora Vapor Moderna. Used in the naming of modern steam locomotives by Porta, such as LVM800.
Man Hole - An oval opening in the boiler plate allowing access for inspection and washing out. Normally large enough for a person to enter the boiler.
Man Hole Door - A solid oval piece of metal with a threaded shaft extending from the middle. The door fits through a man hole and butts against the inside of the outer boiler plate. A clamp fits over the shaft which is bolted down sealing the door against the boiler plate.
Magnetite - An iron based substance formed when levels of dissolved oxygen in boiler water are very low and alkalinities are high. Magnetite forms a layer of grey to black coloured material on internal boiler surfaces giving added protection against corrosions, caustic embrittlement and fouling.
MINAZ - Cuban Ministry of Sugar.
Mobile Sludge - Any solids held in suspension within the boiler water. Porta Treatment, when applied correctly, ensures these solids do no adhere to any boiler surfaces, rather at the slightest circulation current the solids will move.
MSTRS - Modern Steam Technical Railway Services, company operated by Nigel Day.
Mud - Solid particles contained within feedwater. These generally collect at the low points of the boiler where they form a sticky mud like substance. This mud is largely immobile and thus causes localised overheating and circulation problems. Much the same as clay.
Mud Hole - An oval opening (approximately hand sized) in the boiler plate allowing access for inspection and washing out.
Mud Hole door - A solid oval piece of metal with a threaded shaft extending from the middle. The door fits through a mud hole (approximately hand sized) and butts against the inside of the outer boiler plate. A clamp fits over the shaft which is bolted down sealing the door against the boiler plate.
N&W - Norfolk & Western Railroad, USA.
NYC - New York Central Railroad, USA.
PBR - Puffing Billy Railway, Australia.
pH - Strictly this is the measure of the power of the concentration of hydrogen ions. In general terms it is a measure of acidity and alkalinity.
Priming - Boiler water is carried as a more or less continuous stream into the steam circuit by steam escaping past the throttle valve. The normal causes include an over-full boiler or rough driving. It is not the same as carryover.
ppm - parts per million, a way of expressing the amount of a substance in a liquid in the terms milligrams (of substance) per litre of liquid.
ppt - parts per thousand, a way of expressing the amount of a substance in a liquid in the terms grams (of substance) per litre of liquid.
PT - Porta Treatment, an advanced internal boiler water treatment regime.
Reflex Gauge Glass - A form of gauge glass considered to be best practice for steam boilers. A flat glass on the outer side and prisms on the water side giving a very clear indication of the water level.
Reverse Osmosis - The forcing of impure water through a semi permeable membrane across which salts and other impurities cannot pass. In other words it can be seen as a water purifier.
RFIRT - Ramal Ferro Industrial de Rio Turbio, 75cm/2'6" gauge coal railway in the south of Argentine Patagonia. Formerly the most southerly railway in the world.
Santa Fe - Locomotives with a 2-10-2 wheel arrangement.
SAR - South African Railways.
Schroeder Embrittlement Detector - See Caustic Embrittlement Detector.
SMR - Snowdon Mountain Railway, UK.
Steam Contamination - In normal operation steam passing the throttle valve is far from pure. It will contain water droplets carried along in the “steam wind”. These droplets contain dissolved and suspended solids. Such particles build up in passages, ports, valve and piston heads/rings, gland packings and similarly in auxiliaries. Contaminated steam leads, amongst other things, to oil contamination. The contaminated oil can act as a fine grinding paste with obvious detriment to the locomotive.
Soft Water - Water with a low mineral (impurity) content.
Steam Contamination - In normal operation steam passing the throttle valve is far from pure. It will contain water droplets carried along in the “steam wind”. These droplets contain dissolved and suspended solids. Such particles build up in passages, ports, valve and piston heads/rings, gland packings and similarly in auxiliaries. Contaminated steam leads, amongst other things, to oil contamination. The contaminated oil can act as a fine grinding paste with obvious detriment to the locomotive.
SNCF - La Société Nationale des Chemins de Fer, French National Railways.
Tannin - A naturally occurring substance processed by the industrial processing of plants (principally trees) which when concentrated displays various properties such as dissolved oxygen absorbency. Tannins are also used in the leather industry to dye leather products. Dissolved in water tannins form various types of tannin acid thus relying solely on tannin to treat boiler water is not a good idea. It is also important to note 'tannin' is a generic term. Different tannins, that is tannins from different plants, will have different properties and capabilities, such as dissolved oxygen absorbency capacity or the ability to combat caustic embrittlement.
Technically Pure Steam - Defined in this context as containing less than 2ppm of contaminants of all sorts.
TDS - total dissolved solids, a measure of the amount of substances dissolved in a liquid. Often quoted in ppm or ppt.
TSS - total suspended solids. As the name suggests this is a measure of all material suspended in a liquid. Can be quoted in a variety of ways including ppm, ppt or % by volume etc.
Thermo-Mechanical Design - The design of components to withstand heat stress and thus premature failure of the materials.
TIA - Traitement Integral Armand. An internal boiler water treatment regime developed by SNCF.
Tranex Turismo S.A - South American company; owner of FCAF.
Tubular Gauge Glass - The traditional form of gauge glass. A tubular glass through which the boiler water shows the level. Much more prone to failure than reflex gauge glasses.
Wayside Treatment - Any treatment of feedwater carried out prior to the water be transferred to the locomotive's water tanks.
Washout - The process of draining a boiler by removing all drain plugs, mud, hand and man hole doors then flushing pressurised water through to remove any solids precipitated out of the boiler water as mud or scale. Mechanical assistance may be required to remove the solids found. Generally of two forms - cold (uses cold pressurised water) or hot (uses hot pressurised water).
WCR - West Coast Railway, Victoria, Australia.
W&LLR - Welshpool and Llanfair Light Railway, UK.
WLLR - Welshpool and Llanfair Light Railway, UK.
Zeolites - Microporous crystalline solids with well-defined structures. Used in lineside treatment to filter unwanted minerals from water.